Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 291810
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1110 AM MST Thu Jan 29 2015

UPDATED AVIATION SECTION

.DISCUSSION...
Areas of freezing fog persist this morning, mainly along the hi-line
and especially the Havre area. Elsewhere, clear skies prevail over
the CWA as a shortwave ridge aloft traverses western MT. Fog is
shallow and is expected to mix out with diurnal heating. Inherited
forecast remains on track.

&&

.AVIATION...
UPDATED 1810Z.
Dry northwest flow aloft will continue. Areas of dense fog will also
persist across portions of northern Montana. Fog will lift during
the afternoon but will likely redevelop at KHVR after 00z. Surface
winds will be light. VFR conditions prevail with isolated MVFR/IFR
conditions where fog is present.

&&

.PREV DISCUSSION...
/ISSUED 420 AM MST Thu Jan 29 2015/

Today through Saturday...Weak high pressure aloft will keep the
area dry and slightly warmer than normal through Friday, but a
disturbance will bring a shot of more wintry conditions by
Saturday. Clear skies and light winds have helped patchy fog to
form across much of north central and southwest Montana, which
should linger through this morning. Although no areas are
currently reporting dense fog, brief periods of locally dense fog
cannot be ruled out. Otherwise, skies will remain mostly clear to
partly cloudy through Friday with temperatures mostly 5 to 10
degrees above normal. A weak shortwave trough will then break down
the ridge as it moves southeast out of the Gulf of Alaska Friday
night. Mid and high level cloudiness will increase over the area
during this time, as breezy southwest winds keep temperatures a
bit warmer than normal. The shortwave with its associated Canadian
cold front will then move through Montana on Saturday, bringing
cooler than normal temperatures (highs in the 20s) and a good
chance of snow to most of the area. (Far southwest Montana -
southwest of a Butte-to-Bozeman line - will remain warmer than
normal and mostly dry.) Forecast snow amounts appear to be fairly
light at this time (1 to 2 inches at the most), as the disturbance
is expected to move quickly through the area, but northerly winds
will become somewhat breezy, potentially causing localized blowing
snow. Although unlikely at this time, this situation will continue
to be monitored for possible winter weather highlights.
Coulston

Saturday Night through Thursday...Light snow showers will
continue Saturday night as an upper-level disturbance continues
to move through the area. Additional snow accumulations Saturday
night into Sunday morning will be less than an inch. Beginning on
Sunday, the flow aloft becomes west-northwesterly as a Pacific
weather system pushes into the Northern Rockies. Increasing
Pacific moisture and milder airmass associated with this system
will move over a cooler airmass at the surface across north-
central and southwest Montana with the possibility for mixed
precipitation on Monday morning, however forecast confidence
remains low.

Though long-range forecast models indicate that an active weather
pattern may persist beginning Monday and continuing through much
of next week, there remains a lot of uncertainty regarding
temperatures, precipitation coverage and amounts. The ECMWF is the
colder and wetter solution, while the GFS keeps drier, yet
unsettled northwest flow over the Treasure State with temperatures
near seasonal averages. Given these differences, have kept PoPs
near climo and temperatures slightly cooler than seasonal
averages. MLV

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  46  28  44  23 /   0   0   0  20
CTB  44  26  44  20 /   0   0   0  30
HLN  42  21  40  19 /   0   0   0  10
BZN  40  19  38  17 /   0   0   0  10
WEY  35   9  36   6 /   0   0   0   0
DLN  44  22  43  21 /   0   0   0  10
HVR  39  23  40  21 /   0   0   0  30
LWT  43  24  40  19 /   0   0   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

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